Field of the Disclosure
The present disclosure relates generally to processors and more particularly to low power states for processors.
Description of the Related Art
An important objective for modern processor designs is minimizing consumption of power. Accordingly, a processor can employ one or more low-power states, wherein the processor consumes less power and performs at a reduced rate of operation relative to an active state. For example, an x86 processor employs a set of power states, referred to as C-states, with the C0 state corresponding to a fully active state and states C1-C6 corresponding to low-power states. For some low-power states (e.g., the C6 state) the processor performs minimal or no operations. In order to ensure proper execution of software at the processor, prior to entering such a low-power state the processor can save state information stored at one or more registers of the processor to memory. Upon exiting the low-power state, the processor restores the state information to the one or more registers, allowing the software to continue execution from the point where the low-power state was entered. However, the transfer of state information to and from memory consumes power, reducing the efficacy of the low-power state.